Mechanical characterization of MgB2 thin films using nanoindentation technique

Mechanical properties of MgB2 thin films deposited by RF magnetron sputtering technique have been studied. MgB2 thin films were deposited approximately 300 nm on Si substrate above room temperature, and the thin films were subsequently annealed. Great care has been taken to reduce O2 in the chamber during deposition. Structural and mechanical properties of MgB2 thin films were investigated using the Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and nanoindentation techniques. Unloading segments of nanoindentation curves analyzed using Oliver-Pharr method. Both reduced elastic modulus and nanohardness values show load dependence, i.e., indentation size effect (ISE). Proportional specimen resistance (PSR) model was used to calculate the load independent nanohardness value. Load-independent hardness value was calculated using the proportional specimen resistance (PSR) model. XRD and SEM results show that the MgB2 thin films have fine grain size. Nanoindentation results show that hardness and elastic modulus values were 11.72 GPa and 178.13 GPa, respectively.